1. Field of the Invention
The present invention relates to an apparatus for applying heat to a pipe coil. More particularly, it relates to an oil removing apparatus and to the oil removing method for removing the oil adhered to the inside of a pipe wound in a coil by heating the pipe.
2. Description of the Prior Art
During the manufacturing process of a pipe coil formed by coiling a long size metal pipe of fine diameter, a kind of oil, for example rolling oil, adheres over the inner and outer walls of the pipe. When such pipe coil is treated by, for instance, bright annealing in a heat treatment apparatus, the oil over the outer surface can be vaporized and removed by heating. But the oil inside the pipe is not discharged and remains. Accordingly, work has been carried out to remove the above-mentioned oil prior to the heat treatment of the pipe coil. For instance, the gas for removing the oil is fed into the pipe at one end of the pipe coil. The feeding of the gas vaporizes the oil inside the pipe and the vaporized oil is discharged from the other end of the pipe together with the gas.
In some cases, however, the pipe coil is exceedingly long, for instance, a number of ten thousands of meters. Accordingly there is a problem that it takes a very long time to vaporize the oil in the whole area of the inside of the pipe and to discharge it. Also if the removing work is ended in too short a time, some of the oil remains inside the pipe. The remaining oil produces another problem that when the user of the pipe as a product pours contents, for instance, refrigerant for an air conditioner, into the pipe, the oil contaminates the content.